merge r6621 from branch 2.1 to trunk

bug 1742 fixed: if the EXIF functions are not available:

1) display a warning (but not an error)
2) avoid to try to read EXIF data



git-svn-id: http://piwigo.org/svn/trunk@6622 68402e56-0260-453c-a942-63ccdbb3a9ee

admin/themes/default/default-layout.css

@@ -822,7 +822,7 @@ h2:lang(en) { text-transform:capitalize; }
 /**
  * Informations box in administration
  */
-.infos, .errors {
+.infos, .errors, .warnings {
   text-align: left;
   margin: 5px;
   padding: 10px 50px 10px 10px;
@@ -845,7 +845,13 @@ h2:lang(en) { text-transform:capitalize; }
   background-image: url(icon/errors.png);
 }
 
-.infos li, .errors li { list-style-type:square; }
+.warnings {
+  color: #ee8800;
+  background-color:#ffdd99;
+  background-image: url(icon/warnings.png);
+}
+
+.infos li, .errors li, .warnings li { list-style-type:square; }
 .infos .submit {margin-left:30px;}
 
 .checkActions {text-align:left;padding:0;margin:0;}